In warmer biomes with TaN, when it does snow during the winter currently, snow does not stack up, even with this mod installed. Would it be possible to add support for TaN to allow snow to pile up in the winter in all biomes that it snows in during the winter?

The mod does have an API you can build against. https://github.com/Glitchfiend/ToughAsNails/tree/TAN-1.12.x-3.x.x/src/main/java/toughasnails/api